GB 796,475 describes an oil filter which for a long time formed the market standard in the category of lubrication filters. The development in combustion engines has, at least for private cars and trucks, gone in a direction towards engines with higher performance and higher operating temperatures. The requirements on the lubrication oil's quality and the system for purification of the same have also increased accordingly. In many cases the problem is solved with the help of more frequent oil and filter changes. The high quality oil contains many chemical additives which make it expensive to produce and at the same time imply a load on the environment. Used lubrication oil is often destroyed by burning in plants having poor or no cleaning. The normal reason necessitating the change of lubrication oil is that the oil is saturated with fine particles which the engine's filter system is incapable of collecting.
The increased use of hydraulic oil for different systems and arrangements also brings with it a considerable load on the environment, for example when piston seals are damaged by particles in the oil, leading to leaks.
Another field of use for oil is as insulating fluid in transformers. Due to the occurrence of particles and moisture in the oil, arcing can occur in the fluid. The insulating fluid therefore has to be changed or filtered clean at regular intervals.
SE 450 650 describes an arrangement for filtering of combustion oil for diesel engines. The arrangement accomplishes an effective separation of particles and water droplets from the combustion oil but, due to the large flow resistance, this arrangement has a limited field of application.
Present filter arrangements lack the flexibility required to be effective at differing oil temperatures, viscosities and degrees of impurity.